Recently, the first large-scale double-blind, placebo-controlled study of a selective serotonin reuptake inhibitor (SSRI) antidepressant in depressed adolescents was completed (Emslie et al., 1997) That study demonstrated efficacy for fluoxetine in non-AUD adolescents with major depressive disorder (MDD). Our own research group recently completed a first double-blind, placebo-controlled study of fluoxetine in adults with comorbid MDD and alcohol dependence (Cornelius et al., 1997). That study demonstrated efficacy for fluoxetine in decreasing both the depressive symptoms and the alcohol use of adult depressed alcoholics. Our own research group also recently completed a pilot study involving open label fluoxetine in adolescents with comorbid AUD and MDD. That pilot study demonstrated within-group efficacy for fluoxetine for decreasing both the drinking and the depressive symptoms of that population, and suggested that fluoxetine is a safe medication in this population (Cornelius, et al., In Press). However, to date, no double-blind, placebo-controlled study of any SSRI medication has been conducted in adolescents with a comorbid AUD and MDD. In this proposed study, a first large scale prospective double-blind, placebo-controlled study will be undertaken involving the SSRI medication fluoxetine versus placebo in the treatment of adolescents with an alcohol use disorder and major depression (AUD/MDD). The goals of the study include the following: 1) to compare the efficacy of the SSRI medication fluoxetine plus Treatment As Usual (TAU) to placebo plus TAU for the alcohol use and the depressive symptoms of an adolescent sample (ages 15 to 18) of subjects with comorbid diagnoses of an AUD and MDD; 2) to assess specific predictors of medication response in that study; and to perform a preliminary evaluation of the longer-term efficacy of fluoxetine in these patients, in a 9-month naturalistic follow-up period beyond the 3 month acute phase study. We hypothesize that fluoxetine plus TAU will demonstrate efficacy for decreasing both the drinking and the depressive symptoms of this population.